Synthesis gas is a gas comprising carbon monoxide and hydrogen, and it is used, for example, as a fuel gas or as a feedstock for the synthesis of methanol, ammonia or hydrocarbons, which latter synthesis yields gaseous hydrocarbons and liquid hydrocarbons such as gasoline, middle distillates, lub oils and waxes.
The oxygen-containing gas applied as oxidiser is usually air or (pure) oxygen or steam or a mixture thereof. Further, in order to control the temperature in the gasification zone a moderator gas (for example, steam, water or carbon dioxide or a combination thereof) can be supplied to the zone. Those skilled in the art will know the conditions of applying oxidiser and moderator gas.
Further, the gasification process can be carried out at any suitable pressures, for example at 0.1-12 MPa abs.
In particular, the invention relates to a burner as described in the foregoing, wherein a hydrocarbon-containing liquid or gas is applied as fuel.
For example, (heavy) residue feedstock or natural gas can be used as fuel.
According to an established process, synthesis gas is produced by partially oxidising in a reactor vessel a fuel such as liquid hydrocarbon, in particular heavy oil residue, at a temperature in the range of from 1000.degree. C. to 1800.degree. C. and at a pressure in the range of from 0.1 MPa to 6 MPa abs. with the of an oxygen containing gas.
Synthesis gas will often be produced near or at a crude oil refinery because the produced synthesis gas can directly be applied as a feedstock for the production of middle distillates, ammonia, hydrogen, methanol or as a fuel gas, for example, for heating the furnaces of the refinery or more efficiently for the firing of gas turbines to produce electricity and heat.
It is known to apply burners in partial oxidation processes of hydrocarbon-containing fuel which are provided with cooling channels and are cooled by a cooling fluid (e.g. water) flowing through the channels. Reference can e.g. be made to EP-A-0,545,281 disclosing a multi-orifice burner applicable in partial oxidation processes of hydrocarbon-containing fuel which comprises three or more concentrically arranged tubes, having a conical tapering at the burner exit and hollow wall members with internal cooling fluid (e.g. water) passages. A cooling chamber for cooling fluid is arranged in the rear of the burner surrounding the burner exit.
The rear side is covered with a layer of ceramic plates arranged next to one another.
However, the capital expenditure and maintenance of a fail safe water-cooled system is significant. Further, it has appeared that in large burners problems arise with respect to withstanding the cooling water pressure when the reactor pressure is at ambient.
Instead of comprising internal cooling fluid passages, burners may be provided with a suitable ceramic or refractory lining applied onto or suspended by a means closely adjacent to the outer surface of the burner (front) wall for resisting the heat load during operation or heat-up/shut down situations of the burner.
Reference can e.g. be made to EP-A-0,312,133 disclosing a ceramic burner for use in partial oxidation processes of hydrocarbon-containing fuel.
This known burner comprises a burner head which is provided with a ceramic burner mantle protruding into a reactor through a refractory dome. The mantle is connected at one of its ends to the burner head and the protruding mantle separates the burner internals from the reactor environment. There are no separate channels for cooling fluid such as water.
However, it has appeared that the lifetime of this known burner is restricted, since the ceramic mantle is not able to stand thermal stresses and the ceramic material goes to pieces after starting-up the burner. Further, the choice of the ceramic material is critical, only a limited number of ceramic materials can be applied.
It is an object of the invention to provide a burner with a long lifetime which does not require separate cooling channels or passages for cooling fluid and which has virtually no scale-up limitations, is relatively cheap and virtually maintenance-free.
It is another object of the invention to provide such a burner which can operate at severe reactor conditions and limits the heat flux from the flame in front of the burner to the reactor dome and wherein the choice of ceramic materials is not restricted to specific ceramics.